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3.15 rear end

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Rambler Joe View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rambler Joe Quote  Post ReplyReply Direct Link To This Post Topic: 3.15 rear end
    Posted: May/11/2022 at 10:44am
An eBay seller has a 3.15:1 ring and pinion set for a 60-64 Rambler Classic. I have a '66 Classic, and need those gears. Anyone know if they'll fit?
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SC397 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SC397 Quote  Post ReplyReply Direct Link To This Post Posted: May/11/2022 at 11:17am
Here are more answers that you need.
Is the ring and pinion out of a AMC20 or AMC15?
Does your car have the AMC20 or AMC15?
Normally, cars with 6 cylinders had the AMC15 and the cars with V8's had the AMC20 differentials.
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Rambler Joe View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rambler Joe Quote  Post ReplyReply Direct Link To This Post Posted: May/11/2022 at 11:40am
The seller indicated the set will work with the Classic, Rebel, and Ambassador V8, also the '64 Classic with a six. I guess that means it's an AMC20 set?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sonic Silver Quote  Post ReplyReply Direct Link To This Post Posted: May/11/2022 at 11:48am
I didn't think that 3.15 was available on the AMC 15 and was AMC 20 only. Someone correct me if wrong.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amc67rogue Quote  Post ReplyReply Direct Link To This Post Posted: May/11/2022 at 2:53pm
 You are correct.
Keith Coggins 67Rogue X code
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Rambler Joe View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rambler Joe Quote  Post ReplyReply Direct Link To This Post Posted: May/11/2022 at 6:52pm
I have the 327 4bbl in my '66 classic (wagon) and the rear end with 3.15:1 gears came from a '65 with a 272 automatic transmission, so it must be an AMC20.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PROSTOCKTOM Quote  Post ReplyReply Direct Link To This Post Posted: May/11/2022 at 10:07pm
This probably in no way covers all the ratios because I know they had some interesting fleet options, but this will cover 99% of the production.

All 7 9/16" axles (aka Model 15) have the axle ratio stamped on the right axle tube housing boss adjacent to the dowel hole.

CodeRatioGears
E3.5812/43
F3.0813/40
G3.3113/43
H2.7315/41

The 8 7/8" axles (aka Model 20) will have the Axle Ratio Code stamped on the differential housing cover flange.

CodeRatioGears
A3.5411/39
B3.1513/41
C2.8715/43
D3.9111/43



Tom

1949 Ford Business Coupe
1969 AMC Rambler Rouge, Tube Chassis Race Car
1974 AMC Hornet Hatchback, Wally Booth Outlaw NPS Race Car Project
1990 Ford F-350 Supercab Dually
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Rambler Joe View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rambler Joe Quote  Post ReplyReply Direct Link To This Post Posted: May/12/2022 at 9:08am
Thanks for the info. I will check it out.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: May/12/2022 at 11:03am
That info is correct from 1970 up for the AMC 20, 1972 up for the AMC 15. Prior to this the axle ratio is identified by a tag on  one of the rear cover bolts with the number of teeth screen printed on as a ratio. For example, 15/43 = 2.87 (divide 43 by 15 and you get 2.8666...). The first number (smallest number) is the number of teeth on the pinion gear, the second the teeth on the ring gear.

Adding to the chart:
AMC 15 : J = 2.37 (19/45) and K = 2.53 (17/43)

There aren't any more AMC 20 ratios, at least not since 1967 (open driveshaft models). Remember, all 65+ six cylinder big cars used the AMC 20 axle. Older TSMs have the 11/39 axle listed as 3.55 instead of 3.54 (39 divided by 11 = 3.54545... Can be rounded to 3.54 or 3.55).

Older cars (torque tube drive) use lower gears in the 50s and early 60s. The 58-66 American used an open driveshaft but a torque-tube type pinion gear with a "big nut" driveshaft yoke. The nut tightened on tapered threads on the end of the yoke to clamp onto the pinion shaft. Same ring and pinion was used on the big car torque tube AMC 15 as on the open driveshaft axle those years. Since not many people swap those gears I didn't look all the ratios up. They went as low as 4.40 (8/35... actually 4.375) in the 1956 big car with 195.6 OHV.
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpnjim Quote  Post ReplyReply Direct Link To This Post Posted: May/12/2022 at 2:43pm
FYI,
there was two different sized ring gear bolts used on M20's:

3/8" bolts through 1967

7/16"  1968 and later

(Thank you to amc67rogue for pointing that out a few years back  Thumbs Up  )
71 P-code 4spd Javelin/AMX
some Jeeps and some Fords
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